Flames* EDIT * - PLEASE READ POSTS BELOW FOR A BETTER METHOD USING EMITTING NULL
I found an image of some flames on Google and then made corresponding clip and bump maps. I made an emitting material using the flames as a light source and then blended that with a null with the fire only at 5% visibility. I found this gave a good mix of light emitted whilst allow you the see through the flames a little. This material was applied to 4 planes throughout the logs as shown below.

Smoke
The smoke is just a .png image of smoke with a diffuse material, and again blended with a null this time with the smoke at 15% visibility. This material was applied to a simple plane in the middle of the logs.

Ashes
The ashes are a mix of 3 elements 1. some little pebbles 2. a displaced shape to look like a heap of small pebbles and 3. a displaced shape with the 'Fire Embers' material from the Mat DB applied.

Tweaks to improve realism
As there are not (as yet ) any emitting double sided thins for Skindigo we always run into the problem that the light emitted for the flame planes is only in the normal direction. In this case out towards the camera and to the right. In order to combat this I had to cheat a little to ensure I also get light emitting to the rear and the left. This was done by simply adding the flames material to areas of the logs as shown below. I can then just flip my grouped fire model along it's red or green axis to ensure these extra lights are not visible to the camera in any particular scene.
The last thing I did was to introduce a small amount of motion blur to the flames to give them that 'roaring up the chimney' look, this was done using Key Frames. I set the default position of the 4 flame planes as 0, moved them up 20mm and set this second position as 1.

And that, as they say, is that! Hope this help some people!

Attachments

Smoke.jpg (7.5 KiB) Viewed 5365 times

Last edited by bubs on Thu Dec 04, 2014 4:26 am, edited 2 times in total.

..I'd like to suggest you slightly change the topic name: there is a plugin for Maxwell called "Fire" which is sort of an integrated renderer, and this could be misleading for those who know ..maybe..."sketchup fireplace"?

@Zom-B - Thanks, I thought about that but you can't blend a null with a null, so my fire was always opaque, but I take your point that it's probably a more correct way to work... but this was just a tutorial on how I achieved what I did, and I am by no means saying this is the only (or correct for that matter) way to do this. Thanks for pointing out my bad Alpha by the way! This fire was never intended to be in close up, it's just a small corner of a larger scene, so I was happy that I was getting away with it!

bubs wrote:@Zom-B - Thanks, I thought about that but you can't blend a null with a null, so my fire was always opaque, but I take your point that it's probably a more correct way to work...

Yes, the idea here is to have a nullMaterial with a emitting texture!

bubs wrote:but this was just a tutorial on how I achieved what I did, and I am by no means saying this is the only (or correct for that matter) way to do this. Thanks for pointing out my bad Alpha by the way! This fire was never intended to be in close up, it's just a small corner of a larger scene, so I was happy that I was getting away with it!

I never aimed to blame you mate
The point here is simply since it is a tutorial, people will adapt this knowledge into different scenes and scenarios and maybe end up with some performance issue (=> noise) that the can't explain to them-self and maybe blame Indigo to be slow...
I simply try to avoid such pitfalls that end up with more problems and threads from new users

This is all stuff that actually belongs into some detailed performance FAQ, but at some point I stopped to beg Glare for such a thing...

Ok Zom-B: I'm trying to do the null emitter.
First of all, in SU we cannot choose null as a base shader, so I just exported a diffuse and I'm trying to set the material directly inside Indigo. What would be the correct workflow to get your nice image n.2?

Pibuz, mine works fine if I set the material type to diffuse, and in the emitter slot I checked 'texture', linked to my image and then set the layer and power as usual. When it exports to indigo I just select the material and change the type from diffuse to null, that's all.

bubs wrote:Pibuz, mine works fine if I set the material type to diffuse, and in the emitter slot I checked 'texture', linked to my image and then set the layer and power as usual.

Do you use a png..or a clip map maybe? I mean, to exclude the non-flames parts..

EDIT
Sorry for the question...it works...I thought I did the same thing yesterday but apparently I didn't..
Testing the subdivisions efficienty for a comparison now: it's not that I don't trust Zom-B: I just want to check if I got it right!

EDIT 2
Bubs: what did you put in the subdivisions slot for your flames' planes?

A note about the subdivision of the emitting quad: you only need to do this when the emitting part of the quad is a small fraction of the overall quad (like in Zom-b's flame texture). For Bub's image, subdivision probably isn't needed.

Some tests.
The scene is exactly the same: same objects, same materials (null emitter), same light settings, same resolution. Only thing changing is the subdivision of the flames' mesh, as indicated in the images.

The best s/pixels and s/seconds rates are gained in the SUBD.10 test, although I think we get the cleanest result for subd.16.. what do you think?